Technical Abstract:
At the National Center for Agricultural Utilization Research, we study the genetics and biochemistry of mycotoxin production in Fusarium as well as the role of these toxins in the plant diseases caused by the producing species. Our efforts are focused on F. graminearum, which produces trichothecenes and causes wheat head blight and maize ear rot pathogen and F. verticillioides, which produces fumonisins and causes maize ear rot. Trichothecenes and fumonisins differ in their chemical structures, the biochemical pathways by which they are synthesized, and their toxic modes of action. However, the toxins are similar in that the genes responsible for their synthesis are organized into clusters of coregulated genes. The fumonisin biosynthetic gene cluster consists of 15 genes and the trichothecene biosynthetic gene cluster consists of at least 10 genes while the. Analysis of the role of the toxins in the virulence of Fusarium indicates that trichothecene production contributes to the ability of F. graminearum to cause wheat head blight and maize ear rot. In contrast, fumonisin production does not appear to have a major effect on the ability of F. verticillioides to cause maize ear rot. The finding that trichothecenes enhance the virulence of F. graminearum suggests that it may be possible to control the plant diseases and mycotoxin contamination problems caused by this fungus by generating trichothecene resistant crops.